Localised corrosion of copper canisters

Abstract

Copper canisters in a KBS-3-type underground repository will be subject to general corrosion and minor localised attack. The form of the localised corrosion will depend on the composition of the bentonite pore water in contact with the canister surface and, in particular, the pH and chloride, sulphate, and bicarbonate ion concentrations. The presence of a passive Cu2O/Cu(OH)2 layer is a pre-requisite for film breakdown and pitting. Literature pitting data have been used to determine whether pitting is possible or whether the environmental conditions will favour active dissolution of the canister. It is concluded that the canister surface will corrode generally and will be subject to only minor localised corrosion in the form of surface roughening.